1 /*
2 * Copyright (c) 2012 Stefano Sabatini
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a copy
5 * of this software and associated documentation files (the "Software"), to deal
6 * in the Software without restriction, including without limitation the rights
7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 * copies of the Software, and to permit persons to whom the Software is
9 * furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20 * THE SOFTWARE.
21 */
22
23 /**
24 * @file
25 * Demuxing and decoding example.
26 *
27 * Show how to use the libavformat and libavcodec API to demux and
28 * decode audio and video data.
29 * @example demuxing_decoding.c
30 */
31
32 #include <libavutil/imgutils.h>
33 #include <libavutil/samplefmt.h>
34 #include <libavutil/timestamp.h>
35 #include <libavformat/avformat.h>
36
37 static AVFormatContext *fmt_ctx = NULL;
38 static AVCodecContext *video_dec_ctx = NULL, *audio_dec_ctx;
39 static int width, height;
40 static enum AVPixelFormat pix_fmt;
41 static AVStream *video_stream = NULL, *audio_stream = NULL;
42 static const char *src_filename = NULL;
43 static const char *video_dst_filename = NULL;
44 static const char *audio_dst_filename = NULL;
45 static FILE *video_dst_file = NULL;
46 static FILE *audio_dst_file = NULL;
47
48 static uint8_t *video_dst_data[4] = {NULL};
49 static int video_dst_linesize[4];
50 static int video_dst_bufsize;
51
52 static int video_stream_idx = -1, audio_stream_idx = -1;
53 static AVFrame *frame = NULL;
54 static AVPacket *pkt = NULL;
55 static int video_frame_count = 0;
56 static int audio_frame_count = 0;
57
output_video_frame(AVFrame * frame)58 static int output_video_frame(AVFrame *frame)
59 {
60 if (frame->width != width || frame->height != height ||
61 frame->format != pix_fmt) {
62 /* To handle this change, one could call av_image_alloc again and
63 * decode the following frames into another rawvideo file. */
64 fprintf(stderr, "Error: Width, height and pixel format have to be "
65 "constant in a rawvideo file, but the width, height or "
66 "pixel format of the input video changed:\n"
67 "old: width = %d, height = %d, format = %s\n"
68 "new: width = %d, height = %d, format = %s\n",
69 width, height, av_get_pix_fmt_name(pix_fmt),
70 frame->width, frame->height,
71 av_get_pix_fmt_name(frame->format));
72 return -1;
73 }
74
75 printf("video_frame n:%d coded_n:%d\n",
76 video_frame_count++, frame->coded_picture_number);
77
78 /* copy decoded frame to destination buffer:
79 * this is required since rawvideo expects non aligned data */
80 av_image_copy(video_dst_data, video_dst_linesize,
81 (const uint8_t **)(frame->data), frame->linesize,
82 pix_fmt, width, height);
83
84 /* write to rawvideo file */
85 fwrite(video_dst_data[0], 1, video_dst_bufsize, video_dst_file);
86 return 0;
87 }
88
output_audio_frame(AVFrame * frame)89 static int output_audio_frame(AVFrame *frame)
90 {
91 size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format);
92 printf("audio_frame n:%d nb_samples:%d pts:%s\n",
93 audio_frame_count++, frame->nb_samples,
94 av_ts2timestr(frame->pts, &audio_dec_ctx->time_base));
95
96 /* Write the raw audio data samples of the first plane. This works
97 * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However,
98 * most audio decoders output planar audio, which uses a separate
99 * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P).
100 * In other words, this code will write only the first audio channel
101 * in these cases.
102 * You should use libswresample or libavfilter to convert the frame
103 * to packed data. */
104 fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file);
105
106 return 0;
107 }
108
decode_packet(AVCodecContext * dec,const AVPacket * pkt)109 static int decode_packet(AVCodecContext *dec, const AVPacket *pkt)
110 {
111 int ret = 0;
112
113 // submit the packet to the decoder
114 ret = avcodec_send_packet(dec, pkt);
115 if (ret < 0) {
116 fprintf(stderr, "Error submitting a packet for decoding (%s)\n", av_err2str(ret));
117 return ret;
118 }
119
120 // get all the available frames from the decoder
121 while (ret >= 0) {
122 ret = avcodec_receive_frame(dec, frame);
123 if (ret < 0) {
124 // those two return values are special and mean there is no output
125 // frame available, but there were no errors during decoding
126 if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN))
127 return 0;
128
129 fprintf(stderr, "Error during decoding (%s)\n", av_err2str(ret));
130 return ret;
131 }
132
133 // write the frame data to output file
134 if (dec->codec->type == AVMEDIA_TYPE_VIDEO)
135 ret = output_video_frame(frame);
136 else
137 ret = output_audio_frame(frame);
138
139 av_frame_unref(frame);
140 if (ret < 0)
141 return ret;
142 }
143
144 return 0;
145 }
146
open_codec_context(int * stream_idx,AVCodecContext ** dec_ctx,AVFormatContext * fmt_ctx,enum AVMediaType type)147 static int open_codec_context(int *stream_idx,
148 AVCodecContext **dec_ctx, AVFormatContext *fmt_ctx, enum AVMediaType type)
149 {
150 int ret, stream_index;
151 AVStream *st;
152 AVCodec *dec = NULL;
153 AVDictionary *opts = NULL;
154
155 ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
156 if (ret < 0) {
157 fprintf(stderr, "Could not find %s stream in input file '%s'\n",
158 av_get_media_type_string(type), src_filename);
159 return ret;
160 } else {
161 stream_index = ret;
162 st = fmt_ctx->streams[stream_index];
163
164 /* find decoder for the stream */
165 dec = avcodec_find_decoder(st->codecpar->codec_id);
166 if (!dec) {
167 fprintf(stderr, "Failed to find %s codec\n",
168 av_get_media_type_string(type));
169 return AVERROR(EINVAL);
170 }
171
172 /* Allocate a codec context for the decoder */
173 *dec_ctx = avcodec_alloc_context3(dec);
174 if (!*dec_ctx) {
175 fprintf(stderr, "Failed to allocate the %s codec context\n",
176 av_get_media_type_string(type));
177 return AVERROR(ENOMEM);
178 }
179
180 /* Copy codec parameters from input stream to output codec context */
181 if ((ret = avcodec_parameters_to_context(*dec_ctx, st->codecpar)) < 0) {
182 fprintf(stderr, "Failed to copy %s codec parameters to decoder context\n",
183 av_get_media_type_string(type));
184 return ret;
185 }
186
187 /* Init the decoders */
188 if ((ret = avcodec_open2(*dec_ctx, dec, &opts)) < 0) {
189 fprintf(stderr, "Failed to open %s codec\n",
190 av_get_media_type_string(type));
191 return ret;
192 }
193 *stream_idx = stream_index;
194 }
195
196 return 0;
197 }
198
get_format_from_sample_fmt(const char ** fmt,enum AVSampleFormat sample_fmt)199 static int get_format_from_sample_fmt(const char **fmt,
200 enum AVSampleFormat sample_fmt)
201 {
202 int i;
203 struct sample_fmt_entry {
204 enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
205 } sample_fmt_entries[] = {
206 { AV_SAMPLE_FMT_U8, "u8", "u8" },
207 { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
208 { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
209 { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
210 { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
211 };
212 *fmt = NULL;
213
214 for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
215 struct sample_fmt_entry *entry = &sample_fmt_entries[i];
216 if (sample_fmt == entry->sample_fmt) {
217 *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
218 return 0;
219 }
220 }
221
222 fprintf(stderr,
223 "sample format %s is not supported as output format\n",
224 av_get_sample_fmt_name(sample_fmt));
225 return -1;
226 }
227
main(int argc,char ** argv)228 int main (int argc, char **argv)
229 {
230 int ret = 0;
231
232 if (argc != 4) {
233 fprintf(stderr, "usage: %s input_file video_output_file audio_output_file\n"
234 "API example program to show how to read frames from an input file.\n"
235 "This program reads frames from a file, decodes them, and writes decoded\n"
236 "video frames to a rawvideo file named video_output_file, and decoded\n"
237 "audio frames to a rawaudio file named audio_output_file.\n",
238 argv[0]);
239 exit(1);
240 }
241 src_filename = argv[1];
242 video_dst_filename = argv[2];
243 audio_dst_filename = argv[3];
244
245 /* open input file, and allocate format context */
246 if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
247 fprintf(stderr, "Could not open source file %s\n", src_filename);
248 exit(1);
249 }
250
251 /* retrieve stream information */
252 if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
253 fprintf(stderr, "Could not find stream information\n");
254 exit(1);
255 }
256
257 if (open_codec_context(&video_stream_idx, &video_dec_ctx, fmt_ctx, AVMEDIA_TYPE_VIDEO) >= 0) {
258 video_stream = fmt_ctx->streams[video_stream_idx];
259
260 video_dst_file = fopen(video_dst_filename, "wb");
261 if (!video_dst_file) {
262 fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
263 ret = 1;
264 goto end;
265 }
266
267 /* allocate image where the decoded image will be put */
268 width = video_dec_ctx->width;
269 height = video_dec_ctx->height;
270 pix_fmt = video_dec_ctx->pix_fmt;
271 ret = av_image_alloc(video_dst_data, video_dst_linesize,
272 width, height, pix_fmt, 1);
273 if (ret < 0) {
274 fprintf(stderr, "Could not allocate raw video buffer\n");
275 goto end;
276 }
277 video_dst_bufsize = ret;
278 }
279
280 if (open_codec_context(&audio_stream_idx, &audio_dec_ctx, fmt_ctx, AVMEDIA_TYPE_AUDIO) >= 0) {
281 audio_stream = fmt_ctx->streams[audio_stream_idx];
282 audio_dst_file = fopen(audio_dst_filename, "wb");
283 if (!audio_dst_file) {
284 fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename);
285 ret = 1;
286 goto end;
287 }
288 }
289
290 /* dump input information to stderr */
291 av_dump_format(fmt_ctx, 0, src_filename, 0);
292
293 if (!audio_stream && !video_stream) {
294 fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
295 ret = 1;
296 goto end;
297 }
298
299 frame = av_frame_alloc();
300 if (!frame) {
301 fprintf(stderr, "Could not allocate frame\n");
302 ret = AVERROR(ENOMEM);
303 goto end;
304 }
305
306 pkt = av_packet_alloc();
307 if (!pkt) {
308 fprintf(stderr, "Could not allocate packet\n");
309 ret = AVERROR(ENOMEM);
310 goto end;
311 }
312
313 if (video_stream)
314 printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);
315 if (audio_stream)
316 printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename);
317
318 /* read frames from the file */
319 while (av_read_frame(fmt_ctx, pkt) >= 0) {
320 // check if the packet belongs to a stream we are interested in, otherwise
321 // skip it
322 if (pkt->stream_index == video_stream_idx)
323 ret = decode_packet(video_dec_ctx, pkt);
324 else if (pkt->stream_index == audio_stream_idx)
325 ret = decode_packet(audio_dec_ctx, pkt);
326 av_packet_unref(pkt);
327 if (ret < 0)
328 break;
329 }
330
331 /* flush the decoders */
332 if (video_dec_ctx)
333 decode_packet(video_dec_ctx, NULL);
334 if (audio_dec_ctx)
335 decode_packet(audio_dec_ctx, NULL);
336
337 printf("Demuxing succeeded.\n");
338
339 if (video_stream) {
340 printf("Play the output video file with the command:\n"
341 "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
342 av_get_pix_fmt_name(pix_fmt), width, height,
343 video_dst_filename);
344 }
345
346 if (audio_stream) {
347 enum AVSampleFormat sfmt = audio_dec_ctx->sample_fmt;
348 int n_channels = audio_dec_ctx->channels;
349 const char *fmt;
350
351 if (av_sample_fmt_is_planar(sfmt)) {
352 const char *packed = av_get_sample_fmt_name(sfmt);
353 printf("Warning: the sample format the decoder produced is planar "
354 "(%s). This example will output the first channel only.\n",
355 packed ? packed : "?");
356 sfmt = av_get_packed_sample_fmt(sfmt);
357 n_channels = 1;
358 }
359
360 if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0)
361 goto end;
362
363 printf("Play the output audio file with the command:\n"
364 "ffplay -f %s -ac %d -ar %d %s\n",
365 fmt, n_channels, audio_dec_ctx->sample_rate,
366 audio_dst_filename);
367 }
368
369 end:
370 avcodec_free_context(&video_dec_ctx);
371 avcodec_free_context(&audio_dec_ctx);
372 avformat_close_input(&fmt_ctx);
373 if (video_dst_file)
374 fclose(video_dst_file);
375 if (audio_dst_file)
376 fclose(audio_dst_file);
377 av_packet_free(&pkt);
378 av_frame_free(&frame);
379 av_free(video_dst_data[0]);
380
381 return ret < 0;
382 }
383